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- Author or Editor: James Schupp x
- HortTechnology x
Trials were conducted in 2009 and 2010 to evaluate the use of a hand-thinning gauge [Equilifruit; Institut National de la Recherche Agronomique (INRA), Montpelier, France] on three cultivars of apple (Malus ×domestica) trees trained to tall spindle. Hand-thinning treatments were applied after June drop to trees with supra-optimal crop loads. Three hand-thinning treatments were applied using the hand-thinning gauge: 1) thinning to ≈6 fruit/cm2 branch cross-sectional area (BCSA) (F value), 2) subtracting the delta value [Δ (an adjustment factor to increase or decrease the number of fruit per BCSA] from the F value (F − Δ), and 3) F − 2Δ. These treatments were compared with a control and a traditional hand-thinning heuristic of spacing a solitary fruit every 7 to 8 inches of branch length. Use of the hand-thinning gauge generally improved fruit weight and maintained whole tree yields when compared with the control. Hand-thinning based upon traditional fruit-spacing heuristics reduced crop density and increased final fruit weight of apple, but significant reductions in yield were observed in two of four studies when compared with the control. We find the hand-thinning gauge a useful tool in adjusting final crop load of apple.
Renewal of limbs by pruning to leave a short, angled, upward-facing stub is common practice for spindle-type apple (Malus ×domestica) training systems. A short, beveled stub cut is thought to stimulate renewal growth from latent buds present underneath the base of the excised branch, and to stimulate smaller, more fruitful renewal limbs with wide crotch angles. We conducted trials over the course of 2 years that involved dormant pruning of ‘Buckeye Gala’ with renewal cuts to compare two stub lengths, 0.5 and 2 cm, and three stub orientations, upward facing, downward facing, and vertical facing, to determine the effects on renewal shoot number, position, angle, and length. We found no clear advantages with either stub length that we evaluated, and there was no improvement in renewal shoot quality with a bevel cut at any orientation. Stub length and stub angle did not influence limb renewal and may be unimportant for training orchard-pruning crews and for machine-learning and robotic pruning.
Studies were initiated in Idaho and New York to determine the effects of Surround, a kaolin clay particle film product recently labeled as a crop protectant for agricultural crops, on fruit maturity and quality of `Fuji' and `Honeycrisp' apples (Malus×domestica) and fruit mineral concentration of `Fuji' apples. Surround reduced fruit weight, red color, and the incidence of sunburn of `Fuji' apples in Idaho. Sunburn did not occur on `Honeycrisp' in the New York study. In that study, Surround had no effect on fruit weight or red fruit color when applied in May and June but reduced fruit weight and red color when applied later. The reduction in red color development observed in both `Fuji' and `Honeycrisp' was not related to mineral nutrients or to a delay in fruit maturity. Surround applications resulted in undesirable residues in the basin and in the cavity of harvested fruit that were not satisfactorily removed by brushing on a commercial packing line. While effective for reducing sunburn, Surround was ineffective for increasing red fruit color of apples.